Routers are data switches that handle connections between different networks. A router identifies the addresses on data packets passing through the switch, determines which route the transmission should take, and then forwards the packets to their destinations. Routers typically operate at the network layer (Layer 3 in the well-known Open Systems Interconnect [OSI] model), using Internet Protocol (IP) addressing and routing conventions.
Advanced routers currently on the market not only route packets, but also offer a variety of additional service features. For example, Cisco Systems® Inc. (San Jose, Calif.) offers the following features in its 12000 Series Routers and Catalyst 6500 Series Switches:                Quality of Service (QoS) control, with tiered levels of service (including committed access rates, congestion avoidance, prioritization and low-latency queuing, rate-limiting and traffic shaping).        Virtual private network (VPN) and tunneling services.        Security services (such as access control lists [ACLs]/packet filtering, unicast reverse path forwarding [uRPF], firewalls, intrusion and traffic anomaly detection, protection against denial of service [DoS] attacks, IPSec encryption and decryption).        Accounting, statistics and billing services.        
The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: